Turbulence in the boundary layer of flow adjacent to a waterborne vessel causes a considerable drag force between the vessel and the sea. It has been discovered that high molecular weight polymers when injected into the boundary layer, reduce the turbulence and the associated drag forces. These polymers in the prior art were initially used only immediately after being hydrated to form a mucilaginous liquid. The polymers when mixed with water, were not stable in storage, so a specific and relatively complex apparatus was required to mix the polymer immediately before its injection into the flow stream; for example, see U.S. Pat. No. 3,286,674 issued Nov. 22, 1966 to Thompson. To meet the need for having the polymer drag reducing agents pre-mixed and instantly available for use, slurries were developed. Slurries in this context are mixtures of one or more polymers, a carrier, a surfactant and a dispersing agent. The carrier is the media in which the polymer is suspended to form a gel like liquid. The surfactant is provided to enhance the mixing of the polymer and water upon injection by decreasing the surface tension of the water when the slurry is introduced into the flow stream. The dispersing agent maintains the polymer evenly dispersed throughout the colloidal mixture. This combination of materials provides a slurry which can be stored and are available for instant use. Upon injection into the flow stream, the resin dissolves or is leached out of the carrier and it performs its drag reducing function.
Unfortunately, the slurries of the prior art have a limited storage life and have a relatively slow rate of solvation which limits their utility and effectiveness. Changes in the pH and temperature cycling of the slurry during storage cause settling of the polymer in the carrier and thus rendering the slurry inoperative. In addition, delays in the solvation of the polymer decrease the effectiveness of the slurry upon injection. Though the prior slurries have included a surfactant to accelerate the solubility of the polymer in the seawater, the surfactants have been dispersed throughout the slurry and not concentrated around the polymer particles where it would be most effective. The result is that the polymer formed pituitous gel string formations of agglomerated resin upon injection. The larger these strings, the more the polymer resists hydration.